Many modern video displays such as the Sony Grand Wega™ television use three microdisplays, one each for the primary colors of red, green, and blue. Each microdisplay can be, e.g., a liquid crystal display (LCD). To display an image on the screen, the LCDs are illuminated by a bright lamp and through a set of lenses and prisms the final image is expanded to fill relatively large screens. The LCDs with lenses and prisms may be referred to as the “optical block” of the TV.
As understood herein, it is difficult at best to manufacture LCDs to have precisely uniform thicknesses, and even very small variations in thickness cause non-uniformity in the screen display such that some areas of the screen might appear to be brighter than others or tinged with artificial color. This undesirable appearance is magnified when the output of the LCD is optically expanded as is done in microdisplay televisions.
Accordingly, the present invention recognizes that a microdisplay uniformity adjustment process should be employed during TV production to compensate for imperfections in LCD thickness. Modern display measurement systems (DMS) or CCD imaging systems accordingly have been provided to undertake such compensation using a method known as “3D gamma” compensation or adjustment. DMS can include digital signal processing circuitry that can perform 3D gamma adjustment through the use of look-up-tables to improve luminance and chrominance uniformity all over the screen. Additional adjustments that may be made include white balance and contrast.
One or more of the above adjustments are undertaken in dark rooms, in which the optical block is caused to illuminate the screen of the TV, with the illumination being analyzed and used to effect the adjustment. With particular regard to 3D gamma adjustment, a calibration computer is operated to “adjust” the display controller chip by effectively “adding” or “subtracting” display element drive offsets (typically stored in the chip's memory) for each region as needed to achieve uniformity, usually with respect to a center region.
The present invention recognizes that owing to typically limited dark room space, the dark room adjustment processes can cause production bottlenecks. As further recognized herein, effecting picture quality adjustments at the level of the optical block can relieve production bottlenecks in the dark room.